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为从微观角度更加直观地研究靶材厚度对透射式激光烧蚀微推进性能的影响,采用刮涂法制作了6种不同厚度的聚叠氮缩水甘油醚/硝化棉(GAP/NC)共混聚合物掺杂红外吸收染料(IR)的烧蚀靶材,基于高速相机和高倍显微镜搭建了羽流观测系统和靶坑观测系统,研究了在纳秒脉冲激光辐照下,烧蚀厚度分别为33μm,53μm,78μm,104μm,125μm和144μm的GAP/NC+IR靶材所产生的羽流流场随时间演变的微观过程和靶坑形貌的微观特征,从而建立了透射式激光烧蚀的微观特征与宏观推进性能的联系,进一步分析了其所表征的推进性能的优劣。结果表明:随着靶材厚度的增加,靶材的前沿喷射物初始速度由2100m/s单调降至1340m/s左右,预示着烧蚀比冲的减小;喷射物中大颗粒凝聚态物质增多,靶坑的体积增大,喷射质量增加,预示着烧蚀产生的冲量和冲量耦合系数的增大;喷射发散角减小,羽流方向性变好,但烧蚀过程对基底的冲击程度增强。
In order to study the influence of target thickness on the micro-propulsion performance of transmission laser ablation from a microscopic perspective, six different thicknesses of polyazide / glycidyl ether / nitrocellulose (GAP / NC) blend Based on the high-speed camera and high magnification microscope, a plume observation system and a pit observation system were set up for the ablation target of polymer-doped IR dye. The ablation thickness under the nanosecond pulse laser irradiation was The micro-evolution of the plume flow field over time and the microscopic features of the pit morphology induced by the GAP / NC + IR targets at 33μm, 53μm, 78μm, 104μm, 125μm and 144μm, The relationship between micro-characteristics and macro-propulsion performance is further analyzed and the pros and cons of the propulsion performance characterized by it is further analyzed. The results show that with the increase of the target thickness, the initial velocity of the target jet decreases monotonically from 2100m / s to 1340m / s, which indicates the decrease of the specific impulse erosion. The increase of the condensed matter in the jet , The volume of the target pit increases and the jet quality increases, which indicates the increase of the coupling coefficient of the impulse and the impulse generated by ablation. The jet divergence angle decreases and the plume directionality becomes better, but the impact degree of the ablation process on the substrate is enhanced .